alt Hacker NewsOld videos suddenly being heavily promoted again on YouTube is interesting. Sometimes there are obvious reasons, like this 6 year old video about the Straight of Hormuz that is recently making the rounds again [1]. Other times I think it's just the chaotic effects and constructive interference of 2.5 billion users interacting with 15 billion videos - like a rogue wave forming in the ocean.
There are two ways that I've noticed though that YouTube tends to consistently suggest older videos. One is when you first discover a new channel that you like and watch a few videos from that channel, YouTube will start recommending older videos from that channel until you've exhausted the back catalog (or lost interest).
The other way I've noticed is that when I hit the like button a video, YouTube will recommend it to me again after some time has passed. This also seems to depend on the type of video. Music videos are almost always recommended again after some time, while news videos almost never are.
I think these mechanisms are effective at driving traffic to older videos. If I look at my home page right now, most of it does tend to be newer content, but I'd estimate about 25% of it is more than a year old.
In response to your complaint about Berm Peak videos disappearing from your feed - obviously I don't know for certain, but is it possible that YouTube did suggest other Berm Peak videos after you watched a bunch of Reevo videos - but you didn't watch them? And that YouTube might have interpreted that as a lack of interest in the channel?
I've got a couple of channels that I consistently watch whenever they put out a new video. And I find that YouTube is really good about putting their videos at the top of my home page whenever a new video comes out.